1. Field of the Invention
The present invention relates to developing apparatuses for developing an electrostatic image formed on an image bearing member with a developer to be a visible image, which is a toner image. A developing apparatus can be used in e.g., electrophotographic image forming apparatuses, for example, copying machines, printers, and facsimile machines.
2. Description of the Related Art
Some conventional developing apparatuses include a developer supplying member supplying a developer to a developer carrying member conveying a developer for causing an electrostatic latent image formed on an image bearing member to be visible.
Furthermore, although after an electrostatic latent image is made visible, some developer remains on the developer carrying member as a history thereof, some conventional developing apparatuses include a developer removing member removing this remaining developer.
When the above-mentioned developer supplying member or developer removing member is contacted with a developer carrying member, multiple repetitions of an image forming operation leads to a larger load on a developer, thereby resulting in a further deterioration of a developer to cause the occurrence of a faulty image.
Then, according to another conventional technique, to decrease the load on a developer, known is the technique that a developer supplying member and a developer removing member are located out of contact with a developer carrying member (Japanese Patent Application Laid-Open No. S63-106768)
In FIG. 6, one example of a conventional developing apparatus of such a construction is illustrated. FIG. 6 illustrates a cross section of a drum-shaped electrophotographic photosensitive member (hereinafter referred to as “photosensitive drum”) 110 as an image bearing member and a developing apparatus 111.
In this example, there is provided in the developing apparatus 111 a developing roller 113 as a developer carrying member conveying a magnetic mono-component toner 112 for visualizing an electrostatic latent image on the photosensitive drum 110. To remove the remaining toner not having contributed to visualization on the developing roller 113, a rotary electrode 114 is disposed out of contact with the developing roller 113, and an alternating current voltage superimposed with a direct current voltage is applied to this electrode 114. Furthermore, to remove the toner 112 on the surface of the electrode 114, a scraping member 115 is contacted with the electrode 114.
Furthermore, a supplying member 116 for supplying the toner 112 to the developing roller 113 is disposed in the proximity of the developing roller 113. By the effect provided by agitation of the supplying member 116 and a magnetic force from a magnetic rubber layer 113A forming the developing roller 113, the toner 112 is supplied.
In the above-mentioned conventional example, however, since the developer is supplied and removed using two parts of the supplying member 116 and the developer removing member (electrode) 114, the developing apparatus becomes larger.
Moreover, on the other hand, since a magnetic force cannot be utilized in a developing apparatus using a nonmagnetic developer, the supply of a developer to the developer carrying member is insufficient.
In addition, when a developer cannot be removed satisfactorily from the developing roller, the history of an antecedent image sometimes remains. Such a history is referred to as a development ghost.